Based on a manga by Shindou L.

How is anime getting worse throughout the years?

Whether anime, as a whole, is declining is debatable but over the years I have noticed rather disturbing trends that are rather dragging it down.
Namely, Extreme Pandering to the Target Audience This is not exactly new, anime- like all media- has an almost innate tendency to give its audience precisely what it wants, which results in carbon copies repeating themselves across seasons.
Nor need this necessarily be a bad thing in itself, there are times when this sensibility for the audience’s needs can help frame issues that are actually very important. What has changed is the demographics that anime is trying so desperately to please.
At one point, anime was targeted at youth at large and so dealt with universal problems even if often in an overly simplified manner.
Even anime that targeted an older audience did so without considering ‘anime viewers’ in particular so much as ‘viewers’ in general. These days, however, a large section of anime is directly aimed at otaku.
As a result, otaku culture- and all the potential creepiness it contains- is glorified.
The hero will be an otaku himself, or at least someone with absolutely zero social skills- to the point of absurdity- who lands himself a harem of hot girls all vying for his affections. Harem is not new either but the way it keeps creeping into other genres and insiduously ruining them does seem to be more common in more recent anime.
With this come all the clichés that again, while not new, gain an added dose of obnoxiousness: the moe, the ecchi, the overpowered loser. While so much of earlier anime was about confronting difficulties and growing- even in the molds that traditional, shounen-type anime allowed; modern anime is often stuck in hormone-filled supidity in which the MC does not actually change because the target audience is also stuck in a kind of perpetual- and very ill resolved- state of adolescence. What used to be innocent even if corny has snowballed into rather uncomfortable, especially when it comes to relationships between genders.
Perhaps one of the most unsavory outcomes is the oversexualization of virtually every single thing.
It is not just fanservice- although that has come to overstep its bounds- but an obsession with reading events as sexual.
The MC can be left entirely bereft of any ability to process speech if he as much as hears vaguely suggestive talk and overreacts to all things that may be even vaguely sexual.
At times it can be amusing but it can reach levels of paroxysm, particularly when it comes to the blatant sexualization of young girls, particularly the infamous ‘imouto’ types whose childish manners and bodies are displayed as sexy. Interestingly, this less than admirable trend can result in very astute self-reflection anime that tackles otaku culture at its worse with gusto and understanding.
Welcome to the NHK does this brilliantly as does Yahari Ore no Seishun in a different but also very relevant manner. Anime is now Secondary to the Source Material This is also nothing new in itself.
Original anime has always been a rarity so it makes sense that a focus on the source material should be a natural result.
But there was a time when anime could stand on its own.
It even built its own canon, apart from the source material, and had enough episodes to properly create a standalone fictional universe.
There were even times when anime arguably surpassed its source material, Revolutionary Girl Utena immediately coming to mind. These anime were conceived in such a way as to have an introduction, a development and a conclusion stages; the entire narrative could be told entirely through the anime proper, with no need to turn to the source. As of late, however, a lot of anime has become glorified commercials for the source material.
This happened for all sorts of reasons, from the fact that anime now adapts a lot of light novels which run many volumes and are still being published; to the way the cour structure assures that even when the source material is concluded, it is impossible to cram its content into a 13 to 26 episode running.
Sequels do exist, of course, but even these very often do not give any actual closure but merely hint at other sequels that may or not take place. What this means is that a viewer can invest a lot of time in an anime series and still have to turn to the source material if they hope to find out how the story ends.
This does not mean that the anime itself is bad but it can be frustrating and reinforces what has already been said about anime specializing and becoming niche. The diehard fan will of course follow the source material but everyone else is bound to feel a bit cheated.
I also find it disencourages buying anime as it means one is getting only part of the story with no assurance that it will ever be concluded in the same format.